Video: Impact Caused Tesla Battery Fire

A fire in a Tesla Model S electric sedan has once again placed a spotlight on the issue of lithium-ion battery safety.

The incident, captured on a now-viral video, occurred after the vehicle rolled down an off-ramp in a suburban area between Seattle and Tacoma, Wash. Soon after it stopped and the driver exited, the car's front end was engulfed in flames.

Tesla told Design News (a sister publication) in an email:

The fire was caused by the direct impact of a large metallic object to one of the 16 modules within the Model S battery pack. Because each module of the battery pack is, by design, isolated by fire barriers to limit any potential damage, the fire in the battery pack was contained to a small section in the front of the vehicle.

A CT scan image of a battery cell shows the breakdown of layers directly below an indentation. A recent report from Underwriters Laboratories Inc. said that such dents in the casing are a possible failure mechanism for lithium-ion batteries. "The resulting high stress/strain will lead to a mechanical failure of the separator (with failure of the casing), allowing for direct contact between electrodes at a distance onlya few layers below the casing surface.”(Source: Underwriters Laboratories Inc.)

all we can do is reduce the likelyhood to an acceptable level commensurate with the potential damage from the fire - a fuel tank fire has to be isolated from the passengers long enough for them to exit the vehicle. I would say the Tesla design, at this stage, is adequate to protect the passengers.

Over 40+ years of driving I can recall seeing quite a few vehicle fires, but, of these, the most common are associated with semi-trailer rear axles. These are caused by brake failures (dragging shoes, broken air lines, etc.) igniting the bearing grease then, in some cases, the tires and, in turn, the trailer and its load. Should be go chicken little over semi trailer brakes?

The problems with lthium-ion batteries can be fixed, just as the problems with gas tank fires in early gas powered vehicles were fixed. Yes, they happen, but they are rare and the causes are readily traced.

The primary issue is a lot of energy in a small space - gas tank, battery, nuclear power plants, coal piles. Do something wrong and it will burn/go critical/whatever.

We can't be sure NOTHING will go wrong - all we can do is reduce the likelyhood to an acceptable level commensurate with the potential damage from the fire - a fuel tank fire has to be isolated from the passengers long enough for them to exit the vehicle. I would say the Tesla design, at this stage, is adequate to protect the passengers. On the other hand, 4" of armor plate around the battery would protect the battery but it would make the product useless for its intended purpose. What's 'good enough?'

Yes, but EV manufacturers benefit from the previous century of experience with automobiles and do not start from scratch as did ICE manufacturers. I expect that to be an advantage for EV manufacturers, particularly for safety issues.

There are so many failures modes a combustion engine car would catch fire as well. At least from what I have witnessed so many times on the side of the road. So let's not jump the gun too quick on this event. No doubt this new technology needs to be made equally safe to all road hazards like this metal object that impacted the bottom. I am sure there are reasonnable qualification requirements to be met by all manufacturers in order to get a car certification, includingTesla. Let's see what will the final report reveal.

According to the NFPA in 2010 there were some 184,500 vehicle fires leading to some 285 deaths and 1440 injuries or one fire per 1,312 registered vehicles which is much worse then Tesla with a record so far of 1 in 20,000. However to your point that the Tesla Model S is a new vehicle and has not accumulated nearly as many miles on average then the overall US average, based on the number of miles driven Tesla does not fare as well. Tesla has a fleet total mileage to date of about 13 million miles and the NFPA stat works out to about 1 fire in 17 million miles driven for 2010. However one should note that the Chevy Volt with a LIB on board has a total fleet mileage of over 300,000,000 miles and no fires that I am aware of. This is much better then the ICE average and would suggest that LIB's at least in their early life in EVs are quite safe.

Update:

It appears that the 13 million miles for Tesla is an old number and the Design News article reports a current number of 83 million miles driven which would make the occurrence rate for fires in the Tesla Model S much less then the ICE average in 2010.

Gasoline, aviation fuel, and other liquid and gaseous fuels have nearly a hundred years of history and billions of examples behind their present day safety. The last real incident that I remember was the 1970's Ford Pinto needing re-positioning of the gas tank so a rear-end collision wouldn't turn into an inferno.

While Teslas look to be some of the most amazing cars around, sporty like the (earlier) European sports cars, and highly touted by the Wall Street boys who all want one (as do I), this exotic battery technology just doesn't have the real-life environmental and practical use hours behind it to have the bugs worked out of it in large-scale applications like aircraft and automobiles.

While an electronic voice warning the passengers to please exit the vehicle as soon as possible may sound comforting to some people, that sounds like a very small band-aid that might not be overly convenient at the time. I'm certain that I've driven by 20,000 vehicles in the last few months and I don't recall seeing any on fire (this includes EV's and hybrids). There does seem to be an endless trail of tire treads, 2x4's, furniture, and other debris littered down the highway. That shouldn't cause a car to burst into flames (or a Concorde).

If Tesla is going to avoid becoming another Edsel/Corvair/Pinto/Explorer poster boy then it's going to have to completely solve any battery issues, whether or not exotic battery chemistry, behavior, and construction are supposed to be Tesla's core competency.

For goodness sake! Please consider that the technology that you are drawing comparisons between differ greatly in their degree of maturity and their ultimate potential. Gasoline engines are over 100 years old. The type of electric vehicles that you are drawing unfavorable comparisons against gas engines are, at best, 20 years old and some of the technology is only 5 years old. EVs are only getting started.

The video is scary, as any car fire is. More scary is the report that the fire dept. used water on the Lithium batteries to put it out. Usually that is a very bad idea. What is the right way to douse a lithium fueled fire?